1. Field of the Invention
The present invention relates to an X-ray exposure device for medical purposes, particularly for exposing an X-ray image by selectively taking a sheet film from a magazine in which sheet films of different length are loaded and sending it to the exposure stage.
2. Description of the Prior Art
For economizing on energy, a popular type of X-ray film changer is designed so that a number of X-ray sheet films are loaded in a magazine, the sheet films are sent to an exposure stage one by one and retracted from the stage after an exposure is taken. However, in this changer the size of the film, the position of the film in the exposure stage and so have several restrictions.
However, the more popular the equipment becomes, the smaller in size users wish it to be.
FIGS. 1 and 2 show an example of the conventional film exchanger for exposing a chest. This drawing includes an X-ray tube 1, a patient 2 to be inspected, a film changer 3 and a stand 4 for the film changer.
FIG. 2 shows the film changer 3 in section. In the drawing, film 5 is of the first size and film 6 the second size different in width from that of the first size film. A supply magazine 7 serves for the unexposed first size film, a supply magazine 8 for the unexposed second film, and a receive magazine 9 for receiving the exposed film 10. The side of each magazine is provided with a rectangular opening for receiving and delivering the films. Suckers or suction devices 11 and 11' are connected to the vacuum pump [not shown] and movable between the position in the drawing and the inside of the magazine with a transport mechanism. Rotatable rollers 12a-12e serve for transporting the film by holding it between them. A guide plate 13 guides the film along the transport route. A front fluorescent screen 14 fixed on the X-ray permeable fixing plate opposes a back screen 15. A sheet film is sandwiched between the screens and exposed. A film stopper 16 supports the lower edge of the sheet film. A film ejecting lever 17 ejects the sheet film after exposure, and a rotatable roller 18 and guide plate 19 transport the exposed film.
For exposing a chest in Japan films of the size 354 mm.times.354 mm and of the size 354 mm and 259mm are used, with the latter film the longer side being used vertically.
However, some patients cannot be exposed with film 354 mm.times.354 mm, especially if the chest and the abdomen are to be exposed at the same time, the chest and the clavicle are after wished to be inspected at the same time, and so on. Hence the opportunity for using the film 430mm.times.354 mm is becoming more and more frequent. Further in Europe as well as U.S.A. the 430 mm.times.354 mm film is usually used for exposing the chest. When film of the smaller size 303 mm.times.252 mm etc. is used for exposing children, a picture with too much wasted space to observe can be avoided. This also contributes to economy.
The conventional device shown in FIG. 2 is designed so that the sheet film which has been stopped with the stopper 16 is clamped between the screens. Hence the distance between the jaw pad of the changer and the upper edge of the film is too large when a film which is shorter than the standard one is used. Thus, it is necessary to raise the changer body in order to make the set position of the film correspond to the part of the patient to be inspected. However, when the changer body is raised the jaw of the patient hinders the exposing of the chest so that the chest of the patient is far from the changer body and it is difficult to obtain a sharp picture.